1. Field of the Invention
The present invention relates to the field of flat panel display technology, and in particular to a repairable gate driver on array (GOA) circuit and a display device for flat panel display.
2. the Related Arts
At present, the horizontal scanning lines of the active matrix liquid crystal display panel are mainly driven by the external IC of the panel. The external IC of the panel can control the horizontal scanning line connected with each level pixel of the panel to charge and discharge level by level. However, the gate driver on array (GOA) use the existing thin film transistor liquid crystal display array process to produce the horizontal scanning driving circuit on the substrate around the display area, which replaces the external IC to drive the horizontal scanning line. The GOA technology can simplify the manufacturing processes of the display panel, reduce the bonding process of the IC in the direction of the horizontal scanning line, have chance to improve the capacity and decrease the product cost, and improve the integration of the flat display panel to make it more suitable for the production of narrow border or borderless display products, which is widely attracted in the field of flat panel display in recent years.
The existing GOA circuit usually comprises multiple GOA units cascaded with each other. Each level GOA unit correspondingly drives one-level horizontal scanning line. GOA unit mainly comprises a pull-up part, a pull-up control part, a transfer part, a key pull-down part, a pull-down holding part, and a boost strap capacitor used to boost potential. The pull-up part is mainly used to output clock signal into gate signal; the pull-up control part is mainly used to control the turning-on time of the pull-up part, which is usually connected with the transfer signal or the gate signal transferred from the former level GOA circuit; the pull-down part is used to pull-down the gate to low potential at a first time, that is, close the gate signal; the pull-down holding part is used to hold the gate output signal and the gate signal (usually called as Q point) of the pull-up part in the off state (negative potential), which usually has two pull-down holding modules working alternately; the boast capacitor is used to twice boost the Q point, which is beneficial to the G(N) output of the pull-up part.
However, the current GOA technology has some limitations. For example, the gate driver circuit of GOA is difficult to effectively repair, and the invalid of the partial gate driver circuit will lead to the failure of the entire display panel and decrease the product yield. Therefore, it is important for the promotion of GOA technology to develop a gate driver circuit with a certain repair ability.